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June 11, 2010 -- Slightly more than 4% of babies born via assisted reproductive technology such as in vitro fertilization (IVF) may have major birth defects, such as heart and urogenital tract malformations, according to a new study.

But U.S. experts are quick to point out that these risks are not much different from what would be expected in the general population. And the risks are much lower than what has been found in some other studies of babies born as a result of fertility treatments. The new research is slated to be presented at the annual meeting of the European Society of Human Genetics in Gothenburg, Sweden.

The study looked at the rate of major and minor birth defects among 15,162 births from 33 French fertility clinics. Parents and their pediatricians filled out questionnaires regarding infants’ health status, and this information was compared with data from national registers and other studies. Children in the study were born via IVF, a process in which egg and sperm are fertilized in a petri dish and then implanted in the woman’s uterus, and/or intracytoplasmic sperm injection (ICSI), which involves injecting a single sperm into an egg. IVF can also be performed with ICSI.

The major birth defects seen in babies born via IVF and/or ICSI included heart defects and malformations of the urogenital tract, such as hypospadias (an abnormality in the position of the opening of the urethra in boys). In the study, 110 children had genetic disorders, including six children with Beckwith-Weidemann syndrome, which is marked by body overgrowth, and may increase risk of certain cancers. Five children also had bilateral retinoblastoma (cancer of the eye’s retina).

Children born via assisted reproductive technology had a five times higher rate for minor birth defects such as angiomas (a benign tumor of small blood vessels causing a red growth on the skin). Angiomas were twice as common in girls as in boys, the study found.

It is not fully understood whether these birth defects or genetic diseases are caused by the infertility treatment itself or the underlying reason for infertility. Follow-up studies are planned, the researchers say.

Major malformations were more common among children born at low birth weights, but not those born prematurely, the study showed. Parental age at conception did not influence the rate of birth defects.

“Fertility doctors must be informed about the increased risks of imprinting disorders and major malformations because if couples raise questions specifically on this topic, they have to answer as precisely as possible,” Geraldine B. Viot, MD, a clinical geneticist at the Maternité Port Royal Hospital, Paris, France, says in an email. Imprinting disorders occur because of a mutation in a gene inherited from either the mother or the father.

“I'm not sure that women and men undergoing [fertility treatment] should be informed systematically about these risks, as couples having children naturally ignore the risk of major malformations,” she says.

What’s more, “our results are not so different from the general population and I consider them rather reassuring as some previously reported studies showed increased risk of major malformations around 9% to 11%,” she says.

Low Overall Risk of Birth Defects With IVF

Zev Rosenwaks, MD, the director of Perelman/Cohen Center for Reproductive Medicine at New York-Presbyterian/Weill Cornell Medical Center in New York, tells WebMD that more information is needed before any conclusions can be drawn about risks associated with assisted reproductive technology.

The rate of multiple pregnancies is often higher in children born after fertility treatment, he says. “Multiples have higher rates of abnormalities, and this may have affected the findings,” he says.

Counseling about possible risks associated with fertility treatment and informed consent are an important part of the fertility treatment process, he says.

“On our first visit, we review the risks,” he says. “I tell them they have to basically look at what their risk truly is and then determine whether they would choose not to have a baby or choose to have a baby despite a possible increased risk of certain birth defects.”

Not all birth defects are considered serious, he says.

“Angioma is a minor abnormality that can disappear,” he says.

“Even in the worst case scenario, the risk [of birth defects] is low,” says Jamie Grifo, MD, PhD, program director of New York University Fertility Center in New York City. “Your risk may be higher because you are infertile or because you are being treated for infertility, but it is still a low number,” he tells WebMD.

“The risks are about the same that you take getting pregnant at home in bed and no one gives informed consent for that,” he says. “Discuss your concerns with your doctor, but don’t be alarmed. Understand the risks and make decisions based on these risks. There are millions of babies and millions of parents who would not be parents if not for reproductive technology."

This study was presented at a medical conference. The findings should be considered preliminary as they have not yet undergone the "peer review" process, in which outside experts scrutinize the data prior to publication in a medical journal.